Timing drift when looping?

When looping a section that I'm working on, I'm getting slowly more and more drift out of time, I've tried disabling effects but nothing I've tried seems to help.

It's seems every time a looped section starts over it goes a couple milliseconds out of sync, after about 30 seconds everything is wildly out of sync between playing tracks, stopping and starting again clears it.

If I copy the same clips so it's just a long section on the timeline with no loop everything is syncing fine.

This started happening on a large template I've been working on, I've tried a small test project with less tracks and it doesn't happen there, but disabling all plugins doesn't fix it on the large project.

Anyone had this happen?

  Thanks, I always have snap to measure on when working with clips. The same section that will drift, I've tried turning it into a grove clip, snap to measure, move it forward and back to make sure it's snapped, and then just extending it 32 bars, no drift at all there, loop the same section, drifting. 

I've also tried just plugging in straight 16 notes in the PRV just to make sure there's nothing off and let that loop, still drifts slowly over time, set the loop start/end points by typing in the numbers to make sure I don't have something slightly off, still drifts.

Every time the loop starts over there's a very small timing difference added, which adds up as the loop plays more times.

My setup is mostly kontakt instances and aimplitube3 + some prochannel stuff, it's unfortunately way to involved to replicate without all the stuff I got going, but thanks.

I have 8 instances of kontakt, drums (Kontakt steven slate platinum) have 15 audio tracks routed from kontakt for separate outs for drums, 3 double tracked guitar libraries also kontakt ( Prominy V-metal, SC Guitar and VIR2 Electricity) with 2 audio tracks each, 1 bass single audio track (Prominy Sr5 bass), 1 solo guitar (Prominy V-Metal) 1 more audio track, and 1 instance of Omnisphere with 2 audio tracks routed out.

The double tracked guitars, bass and solo guitar has an instance of Amplitube3 on them (2 for each double tracked) so 8 instances of Amplitube 3 running.

So 25 audio tracks in all, 10 busses, 3 stereo busses for the double tracked guitars, 1 for toms, 1 for hihats, 1 for cymbals, 1 kick (Sidechain to bass) and a final buss for all drums collected, 1 reverb, 1 echo, 1 for the keys from omnisphere + the metronome and master buss.

What I'm wondering though, is there anything I could have accidentally turned off that could cause this? Like some sync option, PDC option or similar? I don't have any latency when recording other than what's expected for the buffer size I'm running (256) and I'm pegging the cpu at around 40 tops.

I've been using this setup from a project template for a while, it's only started happening after I tweaked the template recently, that's why I'm suspecting I inadvertently clicked something I shouldn't have and save that with the template.

It is a known bug in 8.5.3 that looping over a section with MIDI tracks driving VST instruments will go out of synch.

It is very clear when you combine, say, MIDI driven drums with a rendered audio rhythm track.

I notice it most when practicing drum fills or other parts that require looping for extended lengths of time as I practice the part.

I've seen it exhibit as increasing latency on the instrument I'm playing compared to the pre-recorded tracks; I've also seen it as the existing tracks themselves going out of synch. Usually the pre-recorded audio is "in time" and the midi-driven VST instrument starts lagging. 

Usually takes 5-8 minutes of looping before it is obvious.

I submitted this as a bug report several years ago. I never got any feedback on it. I did not use X1 so I don't know if it is fixed there. I suppose I should try and reproduce it in X2. The reason I haven't is that I just trained myself to not use that method of rehearsal.

brundlefly

It is a known bug in 8.5.3 that looping over a section with MIDI tracks driving VST instruments will go out of synch.

Do you have a previous thread reference for that?


One specific issue I know of that might be relevant to this problem is the Bitbridge bug that adds an empty buffer of audio to the rendering of some 32-bit soft synths (e.g. BFD Eco, Dropzone). I don't recall whether this bug caused a Bitbridged track to go progressively further out of sync on looping, but it's possible.


The workaround would be to use  the 3rd-party JBridge which doesn't have this problem. I haven't checked recently whether the Bitbridge issue was ever fixed.

I'm not using Bitbridge, and not meaning to hi-jack the OP's thread... but I just reproduced this in X2.
My un-scientific steps were:

• Open a mid-size project
• Solo'd my Percussion and Bass buses
• My percussion bus has both pre-rendered audio click track, and 4 midi tracks driving Addictive Drums VST
• I then looped a section which contained 2 bars of 4/4 followed by 4 bars of 7/8
• Pressed "play"
• Sat back and did something else.
• After about 7 or 8 minutes, I heard the snare timing start to get choppy with respect to the click (randomly ahead of the beat)
• After about 9 minutes, SONAR X2 suddenly motor-boated for two seconds, then stopped.

I wasn't even playing along, practicing another part. 
Note: I am not using SONAR's metronome audio click, I am using my own personal pre-rendered click track.
As for the original problem report, it was back in the Sonar 6 days, and last time I tried to dig up a reference, I couldn't find it, so I won't repeat that.

Anyway, if this is anything like what the OP is describing, I consider it a "known" problem. I should probably work up a simple example... but last time I tried that, I could only make it happen with my own larger projects.

Progress so far (all done during leisure time..)

All tracks are 64bits vsti unless specified. Simple instrument track is used. 

All drums are playing a simple 8th beat pattern. Bass and other synt plays the same note transposed up 12 notes (for string/synt), so any out of sync track can be monitored easily. All in 4/4 time.

6 tracks/instances of Session Drummer 3 (where 2 tracks are froozen)
1 track of BFD 2, just play along with one of the presets.
2 tracks/instances of Kontakt Scarbee bass
1 track of Kontakt Scarbee funk guitarist (the most exciting sound for the test :)
1 track of 32bit Synt 1 (added after reading the above BitBridge issue)
1 track of Studio Instrument String

Drums are sent to bus 1 (drums)
Bass to bus 2 (bass)

In each track, including bus, the pro channel default compressor is turned on.

...section is looped for 12 bars, playback at least 10 mins.

No problem of out of sync. Save project.. rest.

This morning when I open the project (it took some time to load).. there is no sound. The audio interface works, playing regular mp3 files, etc.. After a few tries, I decided to open my simpler project - engine works fine.

Opening the test project, now works again. Strange.

Continue test. Export the above tracks to a wave file.

Import back the same wave file into 8 audio tracks. Add Guitar Rig 5, 4 and TH2 to 3 of the audio tracks.

Still running, more than 10 mins now.. no issue yet.

@stickman393 : just read your message .. I'll try to add some diff time signature on my next round.